PSLE
Opal had two ribbons of the same length. She cut the first ribbon into equal parts of length 20 cm and to each part she tied 2 gold balloons. After that, she cut the second ribbon into equal parts of length 25 cm and to each part she tied 3 purple balloons. When she finished tying, she counted that there were 10 more purple balloons than gold balloons. How many balloons were there altogether?

	First ribbon	Second ribbon	Difference	Total
Length of each part	20 cm	25 cm
Number of balloons tied to each part	2 gold balloons	3 purple balloons
LCM	100 cm	100 cm
Number of equal parts	100 ÷ 20 = 5	100 ÷ 25 = 4
Number of balloons for each ribbon per set	5 x 2 = 10	3 x 4 = 12	12 - 10 = 2	10 + 12 = 22

LCM of 20 and 25 = 100

Number of sets of 2 gold balloons in a length of 100 cm
= 100 ÷ 20
= 5

Number of gold balloons in a length of 100 cm
= 5 x 2
= 10

Number of sets of 3 purple balloons in a length of 100 cm
= 100 ÷ 25
= 4

Number of purple balloons in a length of 100 cm
= 4 x 3
= 12

Extra number of purple balloons in a length of 100 cm
= 12 - 10
= 2

Number of sets of balloons
= 10 ÷ 2
= 5

Total number of balloons in one set of 100 cm of gold balloons and one set of 100 cm of purple balloons
= 10 + 12
= 22

Total number of balloons of the two ribbons
= 5 x 22
= 110

Answer(s): 110